Marinovic Welber, Plooy Annaliese, Tresilian James R
Perception and Motor Systems Laboratory, School of Human Movement Studies, The University of Queensland, St Lucia, 4072, Australia.
Exp Brain Res. 2008 Jun;188(2):275-88. doi: 10.1007/s00221-008-1360-6. Epub 2008 Apr 16.
The interception of fast moving objects typically allows the object to be seen for only a short period of time. This limits the time available to prepare the movement. To deal with short preparation intervals, performers are likely to prepare a motor program in advance. Although motor preparation may begin before the target is seen, accuracy requires that certain program parameters are determined from observations of the target. In the experiments reported here we sought to determine the last moment at which information about the distance to move (amplitude) can be incorporated into a program. We employed an empirical protocol that allowed us to examine whether new amplitude information is incorporated discretely or continuously into the program during short intervals prior to movement onset (MO)-the preparation interval. Participants were trained to hit targets at two different distances with movements of a specific duration (180 ms): targets were moving in "Experiment 1" and stationary in "Experiment 2". This method permitted an estimate of MO time. Preparation intervals were manipulated by delivering a stimulus cue for movement amplitude at varying times prior to the estimated MO. Results demonstrated that amplitude information could be effectively incorporated into the program provided the preparation interval was greater than about 200 ms. In addition, the results indicated that amplitude was specified predominantly in a discrete manner, though the number of responses directed towards a central default amplitude suggest that the distance between targets was near to a threshold for continuous specification.
拦截快速移动的物体通常只能在短时间内看到该物体。这限制了准备动作的可用时间。为了应对短准备间隔，执行者可能会提前准备一个运动程序。虽然运动准备可能在看到目标之前就开始了，但准确性要求根据对目标的观察来确定某些程序参数。在本文报道的实验中，我们试图确定关于移动距离（幅度）的信息可以纳入程序的最后时刻。我们采用了一种实证方案，使我们能够研究在运动开始前的短时间间隔（准备间隔）内，新的幅度信息是离散地还是连续地纳入程序。参与者接受训练，用特定持续时间（180毫秒）的动作击中两个不同距离的目标：在“实验1”中目标是移动的，在“实验2”中目标是静止的。这种方法可以估计运动开始时间。通过在估计的运动开始时间之前的不同时间提供运动幅度的刺激线索来操纵准备间隔。结果表明，只要准备间隔大于约200毫秒，幅度信息就可以有效地纳入程序。此外，结果表明幅度主要以离散方式指定，尽管指向中央默认幅度的反应数量表明目标之间的距离接近连续指定的阈值。
